1. Field of the Invention
This invention relates to a method for the production of a film of oxide of at least one member selected from the group consisting of Sn, Zr, Zn, In, V, Cr, Mn, Fe, Co, Ni, and Cu and more particularly to a method for the production of a film of the oxide, which comprises establishing contact between a treating liquid supersaturated with the aforementioned metal oxide and a substrate thereby effecting deposition of the metal oxide on the surface of the substrate.
2. Description of the Prior Art
Metal oxide films have found extensive utility in various industrial fields.
For example, tin oxide films possess excellent rigidity and have been widely used for scratchproofing the surfaces of glass bottles and dinner sets. There are a number of applications which make use of the semiconductive nature of such tin oxide films. Glasses coated with tin oxide films, for example, have found popular utility as transparent electrode plates for liquid crystal cells, frostproof glass, and transparent conductors. They further excel in the infrared reflection property and, by virtue of this feature, have been famed for their full usefulness as cover glasses for solar heat collectors.
Zirconium oxide films, similarly to titanium dioxide films, have found utility as high-refraction films in antireflection multi-layer films.
Zinc oxide films, in a form doped with aluminum, for example, are used as transparent conductor films. Zinc oxide films of the type produced with oriented crystals find popular utility in a broad spectrum of photoelectric conversion devices.
Indium oxide films such as, for example, Sn-doped indium-tin oxide (ITO) films have found widespread utility as in transparent conductor films.
Transition metal oxide films have found popular utility as colored films, magnetic films, and conductor films.
As means of producing such oxide films, the following methods have been adopted.
For the deposition of a tin oxide film on the surface of a substrate, a method which comprises spraying a solution of tin tetrachloride in an organic solvent on a substrate kept at an elevated temperature has long been adopted as an approach suitable for mass production among other methods. In recent years, the so-called CVD method which comprises exposing the surface of a substrate kept at an elevated temperature to the vapor produced by heating tin tetrachloride or dimethyl tin dichloride has been used widely.
For the production of zirconium oxide films as optical material, the method of vacuum deposition is generally adopted.
For the production of zinc oxide films, the vacuum deposition method, the spattering method, and the CVD method which have been heretofore adopted for the production of films of various types find utility.
As means for the production of indium oxide films, the spattering method, for example, has been found acceptable.
As means for the production of transition metal oxide films, the spattering method, the CVD method, the spray method, etc. have been found acceptable.
The conventional methods for the production of metal oxide films described above, however, have a disadvantage that since they require substrates to be kept at elevated temperatures during the formation of films thereon, they are not allowed to deposit metal oxides on substrates of materials incapable of withstanding the elevated temperatures. Further, on substrates which have three-dimensionally irregular surfaces instead of flat surfaces, these methods produce coats of uniform wall thickness only with difficulty and tend to impair the evenness of wall thickness of the produced coats. The spatter method, the CVD method, etc. which require to use voluminous production facilities have a disadvantage that on account of restrictions inevitably imposed on the production facilities, they are prevented from depositing films inexpensively on the surface of large substrates.
The vacuum deposition method indeed enjoys an advantage that it is capable of producing a zirconium oxide film, for example, on the surface of an optical lens with high accuracy. It nevertheless suffers from a disadvantage that it is incapable of producing a zirconium oxide film uniformly on the surface of a substrate having a large surface area or on a substrate having a three-dimensionally irregular surface and it incurs a high production cost because it requires use of expensive devices such as a vacuum device.